code: def _new_chunks(self, inputs, kws=None, **kw):
      if "_key" in kw and self.source_key is None:
          self.source_key = kw["_key"]
      return super()._new_chunks(inputs, kws=kws, **kw)
  
file_path: mars/mars/tensor/fetch/core.py
imports: from ...core import register_fetch_class, OutputType
  from ...core.operand import Fetch, FetchShuffle, FetchMixin
  from ...serialization.serializables import DataTypeField
  from ..operands import TensorOperandMixin
label_desc: Use image node_id 2 for calling the TensorFetch obj's underlying member method code with example usage: obj._new_chunks(inputs, kws) and returns: super